1. Field of the Invention
This invention generally relates to a two mass flywheel for a motor vehicle transmission. Such a two mass flywheel will typically have a first flywheel mass which can be connected to a crankshaft of an internal combustion engine, and the first flywheel mass can be configured to at least partially surround a hub which is a part of a second flywheel mass. The second flywheel mass can also have a portion which is connectable to a friction clutch for driving a transmission shaft. The first and second flywheel masses are configured to rotate in synchronization with one another, and can also generally be connected to one another in a manner which allows for a limited relative rotation between the two flywheels. The first flywheel can be provided with an axial bearing, or thrust bearing for the hub, and, in a circumferential area of the first flywheel, there can be a radial bearing for the hub.
2. Background Information
European Patent 0 476 707 A1 discloses a two mass flywheel, or a flywheel having two halves, wherein a first flywheel is connected to the crankshaft of an internal combustion engine. In the vicinity of its circumference, this first flywheel has a ring which projects laterally. On the inside of this ring there is a radial bearing for a hub, which hub can execute a limited relative rotation with respect to the first flywheel. This hub is also fastened to a second flywheel designed to hold, or engage, a clutch plate. The first flywheel, on its side facing the second flywheel, has a cover plate which supports a first axial, or thrust bearing for the hub and acts as a closure for a chamber surrounding the hub, which chamber is filled with grease. A second axial, or thrust bearing is located relatively close to the axis of rotation of the flywheels on a projection of the second flywheel, which second flywheel extends to the first flywheel.
The grease well of this flywheel device is designed so that the radial bearing is supplied with grease by means of a lubrication passage which runs between the first flywheel and the hub. Because the more centrally located thrust bearing is spatially separated from this lubrication passage, however, the supply of grease to the thrust bearing is less reliable, whereby the thrust bearing closer to the axis of rotation of the flywheels is affected in particular, because under the influence of centrifugal forces, the grease in the flywheel chamber is forced outwardly away from the axis of rotation. Consequently, significant wear of the thrust bearing can be expected.
On the known flywheel device, the two thrust bearings are located in an area of the hub which lies between the axis of rotation of the flywheels and the radial bearing. This positioning, however, provides only a relatively small distance between at least one of the thrust bearings and the axis of rotation. Because of this small distance, the hub cannot be optimally supported against any wobbling motions initiated by the crankshaft of the internal combustion engine.